What places have you bought annual tickets for, and do you find you've gone more often because of it, or has it turned out to be a waste of money?
We have had annual Legoland tickets (we're in Germany) for about 5 years now as the renewal price is so cheap and we always go at least twice a year which makes it worth it.
We're about an hour and 20 mins away from it, so it's definitely a day trip rather than pop down for the afternoon, but last year we went six times, and used the coupons you get with the tickets for taking friends cheaply too, so absolutely got our money's worth!
This year I also got us annual tickets to a national-trust type place which is much nearer, as we go there quite often anyway (there's gorgeous gardens/park with playground, plus a whole section just for children, and various events on during the year which we like to go to). I'm hoping that having the tickets will make me more likely to get off my arse and make us go out as a family at the weekend 